[1S-[1.alpha.,2.alpha.(Z),3.alpha.,4.alpha.[[-7-3-[[[1-Oxoheptyl)-amino]ace tyl]amino]methyl]-7-oxabicyclo-[2.2.1]hept-2-yl]-5-heptenoic acid is a cardiovascular agent useful, for example, in the treatment of thrombotic disease. U.S. Pat. No. 4,663,336, issued on May 5, 1987, describes a synthesis of this compound that begins with [1S-[1.alpha.,2.alpha.(Z), 3.alpha.,4.alpha.]]-7-[3-Hydroxymethyl-7-oxabicyclo-[2.2.1]-hept-2-yl]-5-h eptenoic acid. Preparation of this latter compound is described in U.S. Pat. No. 4,143,054.